The CEO of United Airlines suggests the possibility of merging with competitor American Airlines.

Media reported on Monday, citing sources familiar with the negotiations, that United Airlines CEO Scott Kirby has proposed the possibility of merging with rival American Airlines Group. The report added that Kirby has presented this idea to senior government officials, but it is not clear if any gestures have been made yet, and it is also unclear if actual discussions are taking place. United Airlines declined to comment. American Airlines and the White House did not immediately respond to requests for comment. A potential merger would further consolidate the U.S. domestic passenger market controlled by the four major U.S. airlines. After the market closed, American Airlines' stock rose over 5%, while United Airlines' stock remained flat.